Wheels skipping without chirping?

[rcryniak]

Ever since I loaded the 4x 3-bar tune, my tires don't chirp anymore. They do, however, seem to "skip" between gear changes under WOT, like they've lost traction, but instead of a pleasant chirping, I get the wheels skipping in a series of tiny micropulses of what I presume is traction loss and regain. It's a bit weird. Anyone seen this or have any input?

 

[brucelinc]

Are you sure you are not feeling transmission stutter due to high shift pressure or older transmission fluid? I use the 4X tune and it chirps nicely on the 1-2 shift. I did have an issue a year or so ago where it "felt" like wheel hop on the 1-2 shift. Livernois sent me a revised tune with lower shift pressure and that solved it. However, I then changed the ATF and put the original 4X tune back in and had no further issues. I now do an annual drain/fill of ATF.

 

[mmh64]

I have heard this shifting shudder caused by many things. Including shift pressure and fluid change mentioned above. Mine has done it when I have uneven tire pressure in front. If all my tires are same pressure it won't do it.

 

[rcryniak]

I just had an ATF flush within the past month or two, so that's definitely not it. Frankly, it only happens from a dig, never from a roll, and only where the tires used to chirp, so I'm feeling pretty convinced that it's traction related. However, I also feel pretty much like a noob still, so I suppose I can talk to Livernois and see what they think.

 

[13blacksho]

I just had an ATF flush within the past month or two, so that's definitely not it. Frankly, it only happens from a dig, never from a roll, and only where the tires used to chirp, so I'm feeling pretty convinced that it's traction related. However, I also feel pretty much like a noob still, so I suppose I can talk to Livernois and see what they think.

Are you saying your tires break traction, just with no chirp sound???
Mine will chirp once in a while, but most often on the 1-2 shift they break loose for a fraction of a second but no chirp sound, I'd say it sounds more like the tire scratching the pavement.

 

[rcryniak]

That's it, but in a rapid succession. Almost like a thump thump thump thump feeling when the tires break loose; it feels really weird and unnatural, like the tires are losing traction, finding it, losing it, etc. However, this happens with or without traction control.

 

[SHOdded]

Can you isolate whether this is on a particular side/tire? Is the PTU fluid freeflowing and filled? Could be torque management also. If you detune, does it still happen?

 

[rcryniak]

Can you isolate whether this is on a particular side/tire? Is the PTU fluid freeflowing and filled? Could be torque management also. If you detune, does it still happen?

I assume it's both tires - otherwise it would pull more to one side I'd imagine, right? Feels like both, though I can't tell by sounds. The PTU has not yet been serviced, so I'm unaware of the condition of the fluid there - it's been on my to do list since I read about that here. Currently at 44k miles. I didn't de-tune - but I can tell you that it only started happening when I put the new tune on. I never once got chirping on the new tune - only the skipping feeling. I have been assuming it's just a weird combination of "power expression" and the wheels/suspension, but I'm totally guessing. Is that wheel hop??

I think I'm just soaking everyone's input (will be soaking in some Livernois input here tomorrow) before I do any steps. I don't have time right now to do a lot of experimenting, and would do my best to figure out what I'm dealing with before I make any changes.

 

[SHOdded]

The best thing to do if you can is to get someone experienced with this gen SHO (like bamsho & others, hint hint) to drive your car and see what they think. Good excuse for a meet, I'd say!

 

[rcryniak]

I spoke with Jaimie of Livernois, and he had some insights - he feels it's traction control related. My guess is that the new tune is allowing for great enough potential wheel spin for the computer to activate traction control there. (That explains the difference between tunes, but I'm guestimating.) He said that it sounds like traction control is being invoked prior to a shift to protect the car from wheel spin that might occur with a "particularly firm shift". I mentioned having turned T/C off via the quick-single-press off (not full off), and he said I needed to put it full off, so it'd read "AdvanceTrac Off". He said (in so many words) that they operate as one "cohesive system" and there's no real separation of them. So, I'm going to do a test with "true off" and another with "AdvanceTrac Sport Mode" and let you guys (and Jaimie) know how it turned out.

I hope that's all it is.

 

[rcryniak]

OK, so I finally got to test this again, with ADVANCETRAC OFF.. full off from a 10 second hold of traction control button.. so NO nannies. Still skipped. No chirp, just 3 rapid thumps, then GOOOoooo.... kind of getting annoyed at the issue... any ideas now?

 

[mmh64]

I would change PTU fluid. 44k miles unknown fluid condition. IMO it needs to be addressed even if it's not related to your shudder.

 

[rcryniak]

I definitely need to do the PTU fluid - I actually have it stocked already (was anticipating doing it soon) and got a special MityVac pump to use for filling... uses shop air to pressurize the pump - neat toy. Anyhow, assuming for the moment that's not related (could be?) Jaimie at Livernois mentioned ATF fluid level, quality, viscosity as possible candidates too. I did just have the ATF flushed around the same time as the tune install, so it could be off. It was done at the same place that botched my last oil change when I was sick... so it's not out of the question. I also just did my oil change today (the first one after they had it) and there was dried oil residue outside the filter like it had a slow leak. Sooo... yeah, they overfilled and didn't tighten the filter right so... I'm not willing to assume they got the ATF fluid right at this point. I'll be checking that as soon as I can.

Once I do that, I'll test again, before doing the PTU fluid, and report back. If that solves it, then we know the ATF fluid was off somehow. Either way, I'll do the PTU fluid next. If the ATF fluid change didn't fix it, and the PTU does, then we'll know it was that. Either way, it adds to our common knowledge, so I'm good with doing it step by step. (If I do both at the same time, then we'd not know which thing fixed it, only that one of them did.)

 

[SHOdded]

Did you take a look at the oxygen sensor also when you looked at the oil filter? Missteps in oil changes have been known to **** that sensor over time.

Time to start datalogging with Torque Pro/Forscan etc. to see if there are any clues. The PCM/TCM management is pretty complex, but at least you can spot a limit being hit and being addressed.

 

[rcryniak]

Nope. I didn't think to look at the O2 sensor at all. I have no DTC codes though... does that matter? I don't have a Torque Pro or Forscan but I can log any ODBII parameters via my tuner (I got the "MyCalibr8r Touch" when Livernois still offered them, aka "DashDAQ" by Drew Tech)... I'm assuming that's just fine... so, which parameters should I be logging? I also bought the extra Ford specific codes and parameters from DrewTech, so I can capture pretty much any information imaginable, and make my results available to you guys. I just need to know what to capture.

Edit:

Missteps in oil changes have been known to **** that sensor over time.

I've just started looking through the service manual, and what I found were "heated oxygen sensors" that plug in around that cats? How would the oil leaking from the filter reach them? How would they get ruined? (Just trying to understand how/what, in my noobishness.)

 

[rcryniak]

Also, measured my tread depth... amazing how quickly I go through tires since buying this car lol. More importantly, seeing an uneven treadwear pattern, more worn to the outside of the fronts. Thinking the toe/alignment is off... could that cause my symptoms??

 

[SHOdded]

I've just started looking through the service manual, and what I found were "heated oxygen sensors" that plug in around that cats? How would the oil leaking from the filter reach them? How would they get ruined? (Just trying to understand how/what, in my noobishness.)

Its the wiring that is affected. Oil & dirt gets into the wiring over time, effectively killing the sensor.

 

[rcryniak]

K, thanks for the classification! Still wondering if my apparent suspension misalignment isn't to blame though.

 

[SHOdded]

One way to find out Might as well have wheel/tire roadforce balanced and checked for leaks while you are at it.

 

[SilverSH0]

Its the wiring that is affected. Oil & dirt gets into the wiring over time, effectively killing the sensor.

Say what? The wiring should be coated in rubber that would prevent contamination of the wire itself. The wiring in my Jeep O2 sensors has been coated in dirt/mud/oil for probably 5+ years w/out issues. The rear main has a slight leak so when I'm driving down the road that oil gets slung back right into the wiring. I could see issues if oil was getting into the sensor but not from simply getting onto the wiring (unless there's a connector there).